The present invention relates to medical imaging applications and more particularly to a tool for editing three-dimensional volumes in such applications.
Three-dimensional (3D) volume editing is performed in medical imaging applications to provide for an unobstructed view of an object of interest, such as a fetus face. For example the view of the fetus face may be obstructed by the presence of the umbilical cord in front of the fetal head. Accordingly, the obstructing cord should be removed via editing techniques to provide an unobstructed image of the face. Existing commercial software packages perform the clipping either from one of three orthogonal two-dimensional (2D) image slices or directly from the rendered 3D image.
The editing from image slices is based on drawing a region of interest (ROI) in one slice and automatically duplicating this ROI through other slices. This is preferably implemented by locating a whole slice with arbitrary angles and moving the slice all the way to the outside of the 3D volume to remove all voxels within the moving distance. In the conventional editing technique, one can define arbitrarily shaped boundaries on a 2D slice and back-project pixelwise into the 3D data space forming an axis-aligned (i.e., along the normal vector of the slice) solid. The bits of all visual voxels within the solid are set to false (i.e., set to zero to remove the inside of the ROI volume).
These standard approaches are time consuming because all voxels along the normal vector of the slice have to be calculated within the ROI. If a square is considered as the ROI with N boundary points, this approach needs (N2/16) computations. Moreover, setting the voxels to false within this ROI solid is also time consuming because the neighborhood voxels in this ROI solid could be scattered on different 2D image planes), and therefore the memory access to the ROI cannot be performed in an organized fashion.
Accordingly, what is needed is a system and method for overcoming the above-identified problem. The present invention addresses such a need.
The present invention relates in general to a system and a method for three dimensional (3D) volume editing for medical imaging applications. The method and system comprise the steps of projecting vertices of the at least one ROI in one plane and transforming the data within the at least one ROI to allow all of a plurality of slices on the inside of the at least one ROI to be along one axis of a three axis coordinate system. The method and system also includes representing the inside of the at least one ROI as a plurality of line segments, wherein only two coordinates and the length of a line segment are stored.
A system and method in accordance with the present invention is particularly useful for removing unwanted structure by defining one or more regions of interest (ROI) in freehand from an arbitrary slice of a 3D data volume. In a preferred embodiment, a system and method in accordance with the present invention comprises a fast algorithm to process a set of compact ROI volumes to remove either the inside or the outside ROI volumes. Because the computational complexity is linear to the boundary of the ROI, a system and method in accordance with the present invention can allow 3D volume editing to be faster and more user interactive.
In addition, in an improvement, the edits could be undone in a limitless and straightforward manner (unlimited undo) by simply storing in memory the original volume (i.e., unedited dataset) and a compact link list structure of the edits which have been performed.